Extraction of metals from sulfid ores by treatment with chlorid or sulfur and electrolysis.



No. a9|,a22. Patnted lan. 28, 1902.

' T .1. SWINBUBNE & E. A. ASHCROFT.

ExTnAcTlon 0F uETALs mom ESULFIDHORE'S BY TREATMENT WITH cHLomn 0sSULFUR AND ELEcTnoLvsls.

(Application filed Dec. 8, 1899.

w T Alf/07148) m: Noams PETER5 w. PkomuTl-TQ. wnsumumn. 0.0.,

UNITED STATES PATENT OFFICE.-

. JAMES SWINBURNE AND EDGAR ARTHUR ASHCROFT, OF LONDON,

ENGLAND.

EXTRACTION OF METALS FROM SULFID ORES BY TREATMENT WITH CHLORID ORSULFUR AND ELECTROLYSlS.

SPECIFICATION forming part of Letters Patent No. 691,822, dated January28, 1902. Application filed December 8, 1899 Serial No. 739,684. (Nospecimens.)

T0 to whom it may concern:

Be it known that we, JAMES SWINBURNE and EDGAR ARTHUR ASHCROFT, subjectsof the King of England, residing at Westminster, London, England, haveinvented a cer tain new and useful Improvement in the Extraction ofMetals from Sulfid OresbyTreat: ment with Chlorid of Sulfur andElectrolysis, of which the following is a specification.

Our invention has reference tojthe treat: ment of sulfid ores in the dryway at high temperatures with chlorid of sulfurin connection withelectrolysis. V

In carrying this invention into effect the ore is in most cases run intoa fused salt, such as chlorid of zinc, contained in a converter orchlorinator. Liquid or gaseous chlorid I of sulfur is then introducedinto the bottom of the converter. The chlorid of sulfur is nor mally S01 but it may contain either sulfur in solution or higher chlorids ofsulfur, according to the circumstances of formation. The chlorincontained in the chlorid of sulfur is absorbed by the metal contained inthe ore, and the sulfur contained in the ore and in the chlorid ofsulfur is liberated and distils off. The metallic chlorids so formed maybe then electrolyzed. In most cases this electrolysis is conducted withthe electrolyte in the fused state. The chlorin produced in theelectrolysis is caused to come into contact with sulfur, and the chloridof sulfur produced is condensed into liquid form. The sulfur contents ofthe chlorid employed is liberated at the same time as the sulfurcontents of the ore and may be employed for the regeneration of thechlorid of sulfur. The process is thus cyclic or regenerative as to thechlorid of sulfur, the ore being decomposed into free sulfur and metaland the chlorid of sulfur being regenerated. 1

In some cases the formation of chlorid of sulfur may be simply effectedby'putting the sulfur into the zincchlorid-electrolyzing vats, whereitmelts and floats, and providing the surface temperature of the chloridis not above the vaporizing-point of sulfur the chlorid of sulfurdistils over, more or less free from dissolved sulfur, (S -143 :8 01When it is desired to form the higher chlorids of sulfuror where theabove temperature condition is not obtainable, the chlorin is led intoseparate vessels containing,respectively, sulfur or sulfur monochlorid.

The process is applicable to the numerous sulfid ores in which variousmetals are contained singly or together; but We describe it particularlyin connection with mixed lead, zinc, and silver sulfid ores, which aredifficult to treat by existing metallurgical methods. As an exampleofour process, treatment of lead-zinc-sulfid: ore may be taken. It iscrushed, but not roasted, and it is run into fused chlorid of zinccontained in a chlorinator. The temperature of the mixture may bebetween 500 and1,000 centigrade and may be controlled by regulating theblast of sulfur chlorid.

and, becoming vaporized, bubbles through the mixture of fused chloridand sulfid. The sulfur of the chlorid and the sulfur of the ore come offtogether and are condensed.

If the passage of the chlorid of sulfur is rapid, and especially if thetemperature is low, the vapor generally contains some unaltered chloridof sulfur, which'may be removed from the sulfur by fractionaldistillation and condensed in any suitable vessel. The metallic sulfidin the ores is thus converted into chlo- The sulfur chlorid is run in.at the bottom through an earthenware pipe rid. This chlorid is thenpreferably purified 4 from iron and manganese, as iron would contaminatethe zinc and manganese would accumulate when the process is workedcyclically. We may remove iron by converting it into ferric chlorid,

2FeOl +Cl :Fe Cl and treating the ferric chlorid withzinc oxid,

Fe Ol +3ZnO:Fe O ]-3ZnCl in the wet way. We may remove the manganese bypassing chlorin gas or sulfur chlorid into the fused mass in thepresence of zinc oxid. Both manganese and iron are precipitated then asoxids,

The zinc and lead and other metallic chlorids I thus produced may beremoved from the unchanged gangue by raising the temperature, in whichcase they mostly distil over. The various metals may be separated fromthe fused chlorids or their solutions by substitution. For instance, theprecious metals and antimony may be removed by lead, forming leadchlorid,

If excess of lead is used for extracting the precious metals from leadchlorids, a rich alloy is produced. The lead may be removed from themixed chlorids by zinc, forming zinc chlorid,

Copper may be similarly removed by zinc, and if excess of zinc is usedto extract copper from fused salts the copper comes out in alloy withzinc as brass. The metals may also be separated by fractionalelectrolysis of the fused chlorids or their solutions.

The zinc chlorid to be electrolyzed is while still fused passed into theelectrolytic vat, which contains also in admixture potassium or sodiumchlorid. Metallic zinc and chlorin result from the electrolysis. Thechlorin is passed to some of the sulfur from the chlorinator, thusreforming the chlorid of sulfur, and the metallic zinc is removed byperiodically tapping off. The chlorid of sulfur is preferably formed orcondensed or stored at high level, so that it can be run into thechlorinator by gravity.

In order that ourinvention may be fully understood, we will proceed todescribe it with reference to the accompanying drawings, which show aspecimen scheme of our process applied to lead-zinc-sulfid ore.

Tracing the progress of the ore, it is led into the chlorinator 1, whereit is run into fused zinc chlorid, so as to form asemifiuid mixture. Thechlorinator is of fireclay, preferably glazed inside. A little zincchlorid is melted separately in a ladle and run into the chlorinator,and a little ground sulfid ore is run into it. Chlorid of sulfur is runin from tank 2. The sulfur formed is condensed in the still 3. Thesulfur is subsequently fused to separate the chlorids that have beencarried over with it, which settle out of the fused mass, and is then afinal product. At the final stage of the conversion air is also blowninto the chlorinator to precipitate iron and manganese as oxids.

The air is blown into the converter by an ordinary air-blower and issupplied through the sulfur-chlorid pipe. When the conversion of thesulfide into chlorids is complete, the charge in the chlorinator isallowed to settle, and the clear chlorids of silver,lead,and zincthatis, chlorids free from ganguewith any chlorids of antimony or arsenic,are run into the desilverizing-vat 4, where the silver, an-

timony, and arsenic are taken out by substitution of lead.

4AgCl+Pb :2PbCl +2Ag The rich silver bullion from this vat is a finalproduct. The desilverized lead and zinc chlorids are led to thedeplumbiug-vat5,wl1en the lead is removed by zinc,

The lead is a final product, and the zinc chlorid goes to theelectrolytic vat 6. The other portion of the chlorinator charge orsludge consists of gangue and iron and manganese oxids reduced to theconsistence of mud by fused chlorids. This chlorinator sludge is led tothe desilverizing-vat 7 and then to the deplumbing-vat 6. The materialsare maintained in a fused condition in the desilverizing, deplumbing,and electrolysis vats. The desilverizing and deplumbing processes arequick enough to be carried out before the mass cools, and theelectrolysis-vat is kept hot by the electric current, as in the case ofaluminium; but in the case of zinc chlorid a much smaller surpluselectrical pressure is needed.

Desilverizing, 2AgOl+Pb=PbCl+Ag Depluinbing, 2PbCl +Zn 2ZnOl Pb Afterthat it is cooled and led to the leach in g-vat 9,Where the chlorid ofzinc is dissolved in water. It is separated from the gangue by thefilter-press 10 and by further leaching, and the solution is mixed withpotassium chlorid. The potassium chlorid is to form a double salt withthe chlorid of zinc. This double salt dehydrates on heating withoutforming oxychlorid to any serious extent. The mixture is evaporateddownin the evaporator 11 until the salt is anhydrous and fused in it andthen led to the electrolytic vat 6. In this vat it is electrolyzed,yielding zinc chlorin. The chlorin is led to the sulfurizer 12, where itis converted into chlorid of sulfur.

The sult'urizer is a vessel containing sulfur heated externally nearlyto the boiling-point of sulfur. The chloriu is led so as to blow ontothe surface of the sulfur, and combination takes place easily andquietly. The chlorid of sulfur is condensed in the still 13 and storedin the closed vat 2 on a higher level than the chlorinator.

Chlorid of sulfur has an advantage over chlorin as an agent forsplitting up the sulfid ores in that it is easily stored and handled. Itis easily formed and can be kept in bulk. It would thus not be outsideour present invention to convert chiorin into chlorid of sulfur to getthe advantages of easy handling and storage and to decompose the chloridof sulfur more or less by heat before passing it into the sulfid ore.

In most cases the ore is treated suspended in a bath of fused haloidsalt; but this is not essential. Ores with volatile chlorids-such asantimony or arsenic, or even zinc sulfidmay be treated with chlorid ofsulfur without any bath of fused salt. The ore is then heated above theboiling-point of its chlorid and is then treated with sulfur chlorid.The reaction is as before, sulfur and chlorid of the metal distillingover.

What we claim as our invention, and desire to secure by Letters Patent,is-- 1. The herein-described process consisting in treating sulfid oresin the dry way at a high temperature with chlorid of sulfur S 01 to formchlorid of the metal or metals and free sulfur substantially asdescribed.

2. The herein-described process consisting in treating metallic sulfidsin a bath of fused haloid salt with chlorid of sulfur S 01 substantiallyas described.

3. The herein-described process consisting in treating sulfid ores inafused haloid salt with chlorid of sulfur and producing sulfur ore andso on.

4. The process herein described consisting in electrolyzing a metallicchlorid, thereby producing chlorin, combining sulfur with said chlorinand producing chlorid of sulfur, and then treating heated sulfid orewith said ch10- rid of sulfur, and producing therefrom chlo-' ridof-metal in the ore, and free sulfur.

In testimony whereof we have signed our names to this specification inthe presence of two subscribing witnesses.

JAMES SWINBURNE. EDGAR ARTHUR ASHCROFT.

Witnesses:

E. E. SKINNER, V. HIPWELL.

